Neuropathy is a generic term used to describe diseases of the peripheral nervous system. There are about 200 known different causes of peripheral neuropathies. Although most neuropathies affect all three major classes of nerve fibers to varying degrees, some diseases involve only one or two, and are thus said to be purely or predominantly motor, sensory, or autonomic neuropathies.
Guillain-Barré syndrome (GBS) is an acute illness involving the peripheral nervous system that usually occurs two to three weeks after a flu-like disease or other infection, including Campylobacter enteritis. It is mostly a motor neuropathy, meaning that its symptoms are largely related to the involvement of the motor nerves. Despite the primarily motor nature of the disease, the earliest symptoms may be numbness and tingling felt in the lower extremities followed shortly by weakness of the distal muscles of the lower extremities. The danger occurs when the weakness involves the muscles of respiration. GBS is associated in a proportion of cases with antiganglioside autoantibodies (AGAs) to a wide range of specific glycolipid structures, and also with antibodies to other nerve components including myelin proteins and glycosaminoglycans in some cases, and in other GBS cases, antibodies are presumed to be present but have yet to be formally identified.
Miller Fisher syndrome (MFS) is a variant of Guillain-Barré syndrome, accounting for 5-10% of cases. In one survey, the annual incidence has been estimated at 0.09 per 100,000 population. MFS is characterized by the acute onset of opthalmoplegia, ataxia and areflexia. Anti-GQ1b ganglioside antibodies are the serological hallmark of MFS. The antibodies may arise in some cases through molecular mimicry with Campylobacter lipopolysaccharides. It is now widely accepted that well over 90% of patients with MFS have anti-GQ1b IgG antibodies during the acute phase of the illness. Equally significant is the complete absence of anti-GQ1b IgG antibodies from normal and other disease control groups, indicative of a high level of specificity for this disease association. The antibody titers peak at clinical presentation, decaying rapidly with the course of clinical recovery. Anti-GQ1b IgG antibody titers are also elevated in the acute phase sera of some patients with Guillain-Barré syndrome with opthalmoplegia. The anti-GQ1b IgG antibody marker also identifies a cluster of closely related syndromes, often considered formes frustes of MFS, that have in common the presence of external opthalmoplegia or cerebellar-like ataxia.
The current treatment for GBS, including AGA-mediated cases is intravenous immunoglobulin (IVIg), plasma exchange, or a combination of both. Although some neuropathies like GBS are usually self-limiting illnesses, intensive therapeutic intervention is often needed. Some individuals are left with residual deficits. Other neuropathies are chronic and only symptoms such as pain are treated. There is a great need for additional treatments to improve symptoms and decrease recovery time of antibody mediated neuropathies.